1. Field of the Invention
The present invention relates generally to an apparatus and method for producing mineral wool, and, more particularly, to an apparatus and dry process for producing mineral wool comparatively free from shot, beads, or slugs. The term "mineral wool" is employed in its generic sense and is meant to include wool or fibers formed from rock, slag, fused glass, glass mixtures thereof and other heat liquefiable raw materials capable of being converted into fibers.
2. Description of the Prior Art
In the manufacture of inorganic fibrous material, such as slag wool, glass wool or mineral wool, a molten stream of the desired inorganic material is fiberized by various means, such as by impinging the molten stream on rapidly rotating discs or by impinging a high velocity blast of air or steam against the stream of inorganic material. Customarily the fibers, upon formation, are suspended in a gaseous medium. The fibrous suspension is usually directed into a collecting chamber of some sort wherein the suspended fibrous material is removed from suspension to form a fibrous mass.
The production of inorganic fibers, such as by the aforementioned methods, is customarily accompanied by the formation of a substantial amount of unfiberized material, such as pellets, partially fiberized pellets and fiber bundles or slugs. In many instances, up to 50% and more of unfiberized material is formed during the manufacture of inorganic fibers. This unfiberized material is very detrimental in certain mineral fiber applications, such as where the mineral fibers are used as heat insulation material in paper-enclosed batts, as reinforcing agents in spray-on heat insulation, as fibers in rigid acoustical panels and tiles, or as reinforcing fibers for plastics, friction materials, papers and felts. Accordingly, it is highly desirable to provide an inorganic fibrous material having decreased amounts of unfiberized material.
Heretofore, numerous attempts have been made to provide apparatuses and methods for the satisfactory separation of the fibers and unfiberized material produced in the manufacture of inorganic fibrous material. Both wet and dry separation techniques have been employed. One such "dry" technique which has been utilized in processing mineral fiber involves granulation and the subsequent employment of a series of devices for removing coarse unfiberized material. In this conventional process, much of the finer shot remains trapped in the nodules. This procedure is not satisfactory to produce "clean," i.e., "shot-free," mineral fiber.
It would be highly desirable if an improved apparatus and dry method for de-shotting mineral fiber could be found which avoid the disadvantages of the prior art, and result in the manufacture of relatively "shot-free" mineral fibers at a particularly high rate of production.